Studies On Genetic Features Of Gonadal Differentiation In Half-smooth Tongue Sole (Cynoglossus Semilaevis)

Half-smooth tongue sole belongs to Pleuronectiformes, Cynoglossidae, Cynoglossus, which is a commercially important cultured marine flatfish and forms an important fishery resource in China. Females of half-smooth tongue sole grow two to four times faster than males. The sex determination system of the species is female heterogeneity(ZZ/ZW), and females’ chromosome is ZW, while males’ is ZZ. There are neo-males in the natural populations, the neo-males are significant difference with normal females in length, weight and other aspects, while are not with normal males. The gonadal differentiation of some fishes and amphibians, is very interesting biology question and its molecular genetic mechanisms are rarely explored. If we know the genetic features of gonadal differentiation in half-smooth tongue sole and reduce the percentage of neo-males in cultured population, it will be a method to solve the problem of the low ratio of female fundamentally. We study the genetic features of gonadal differentiation in half-smooth tongue sole, and the results will shed light on exploration of mechanisms for sex determination theoretically and sex-control practically.In this study, 10 half-sib families are set up by utilizing two types of male parents: genetically males and pseudo males which are genetically females. Using microsatellite marker technology and paraffin section technology to study on genetic sex and biological sex in F1 of half-smooth tongue sole, the 15 microsatellite markers were used to identify paternity tests, and the results were analyzed by the software of Cervus 3.0 and R software. The results show that the females were all different into physiologically male fishes in two families with pseudo male parent; in the other 8 families with normal male parent, the ratio of neo-males in individual populations presents continuous distribution, which fits for features of QTLs(Quantitative Trait Loci) typically; the heredity of sexual differentiation is lower, only 0.058. All of these results show that: the pseudo males as parents, which demonstrate full paternal-effects, the female progenies were all different into pseudo males; interfamily selection for improving the genetic advances of sex ratio or genetic evaluation of genetic females different into neo-males by using genetic markers are advantageous over interfacial selection for lower heredity of sexual differentiation.